1. Field of the Invention
In its broadest aspect, this invention relates to attachments which allow precise geocentric leveling of the cant of a projectile barrel prior to firing the projectile. The projectile may be a ballistic type, such as a bullet, or a nonballistic type, such as a rocket or a laser beam. In the following specification the term "firearm" should be taken in its broadest sense as any device for imparting a forward velocity to a projectile. Included in such a definition are catapults, fire hoses, bows and arrows, guns, and laser beams in increasing order of complexity. In a laser beam the projectile is considered to be the photons of light emitted. Applications for such devices abound.
On a smaller scale, the present invention relates to the fields of hunting and target shooting with hand-held weaponry such as firearms or bows and arrows. More specifically, the invention provides an inexpensive and convenient means for accurately aiming such firearms without error due to "canting" or tilting about an axis generally, but not exactly, parallel to the line of flight of the projectile. The invention, as presented here, relies primarily on the user to provide manual correction to the cant of the weapon based upon visual cues provided by the invention.
It is contemplated that the invention could be easily mechanized by connecting the level sensing device, via a servomechanism, to an automatically powered leveling device. Such mechanization of the invention would expand its potential fields of use to include artillery, cannons, and any other device requiring accurate initial aiming of a projectile. Such a modified servo-platform would be particularly applicable to ballistic firearms normally fired from a moving platform such as helicopter gunships or naval vessels. The skilled artisan will recognize many other esoteric potential fields of use for the invention.
In a more mundane and practical sense, it is envisaged that the present invention could easily be manufactured and sold as an inexpensive kit for adding to almost any existing firearm and providing that firearm with convenient level indication means for improved accuracy.
The way the firearm is held by a shooter can have a significant effect on firearm accuracy. As will be geometrically demonstrated later, it is even possible to have an expensive telescopic sight, set perfectly for windage and range, aligned perfectly with target boundaries, aimed precisely at the bulls eye, and held perfectly motionless during firing, and still miss the target.
The accuracy of hand-held firearms is improved by an order of magnitude with the addition of a good telescopic sight. As well as means for magnification of the target, fine adjustments are possible for such effects as windage and range. The scope optics usually provide horizontal and vertical cross-hairs as a visual reference. If the shooter has a good horizontal or vertical reference within the field of view of the scope, it is a relatively simple matter to align the appropriate cross-hair with that reference to assure an accurate shot. A major problem is encountered if the assumed horizontal or vertical reference is not truly horizontal or vertical. In actual hunting practice the presence of true vertical or horizontal references in the environment is rare. In hilly or mountainous country the horizon is often not exactly horizontal. Also, the horizon is often not in the field of view of the target. Tree trunks rarely are exactly vertical in any terrain and thus do not provide a reliable reference. Even stationary shooting targets, as often found on shooting ranges, cannot be depended upon to be perfectly level. As a result the cross-hair mechanism, upon which even expensive telescopic sights rely for leveling and accuracy, is highly undependable.
Many times the only reason telescopic sights work at all is the uncanny ability of the human sense of balance to somehow perceive the vertical in spite of disorienting visual cues. Most hunters and marksmen rely heavily on their inner sense of balance to ensure that the firearm is not canted. Studies of airplane pilots reveal that the human sense of balance is easily confused by a number of influences. Not the least of these is the presence of loud noises such as is common around discharging firearms. The hunter is subjected to a myriad of disorienting influences such as fatigue, wind, rain, cold, rough and uneven terrain. The human sense of balance can easily become confused by even the mildest of the disorienting influences common to hunting and target shooting. This invention eliminates dependence on the easily confused sense of balance.
It will become immediately evident that the unique properties of the apparatus herein disclosed will provide important benefits in many areas. The conversion kit of this invention may be adapted for use in any field in which it is desired to accurately aim a ballistic projectile such as a bullet or even a nonballistic projectile such as a laser beam. As such it will be appreciated that the potential uses are myriad. A comprehensive listing of all the possible fields to which this invention may be applied is limited only by the imagination and is therefore not attempted here. Some of the more obvious applications are mentioned herein in the interest of providing a full and complete disclosure of the unique properties of this previously unknown general purpose article of manufacture. Recreational target shooting and game hunting are seen as the fields most likely to gain immediate and substantial benefit from this invention. It is to be understood from the outset that the scope of this invention is not limited to these mentioned fields or to the specific examples of potential uses presented hereinafter.
2. Description of the Prior Art
The prior art in a few instances has broadly recognized the inaccuracies introduced into the aiming of a hand-held firearm if its firing barrel is not held in a perfectly vertical plane. However, none of the prior art has offered an inexpensive and practical solution which can be easily applied to existing firearm sighting systems.
U.S. Pat. No. 5,005,308 issued to Parks on Apr. 9, 1991, teaches the need for a tilt indicator for firearm scopes and claims a solution based on electric circuitry responsive to the tilting of a mercury switch. This solution of Parks requires an electrical power source for the circuitry involved. By contrast, the instant invention requires no external power source. Parks also shows a mechanical embodiment comprising a liquid leveling device enclosed within the barrel of a telescopic sight. This solution of Parks would require the purchase of a special telescopic sight with the special liquid leveling device built in. In contradistinction, the instant invention requires no special scope or sighting device. Instead, the instant invention provides a simple but effective leveling device that can be added to any existing hand-held firearm sighting system. Additionally, the disclosure of Parks is of interest for his correct assessment that a counter-clockwise cant about the telescopic line of sight will cause the bullet projectile to miss the target low and to the left. The disclosure of Parks is herein incorporated by reference for his discussion of the geometry of the situation.
U.S. Pat. No. 4,214,372 issued to Rusbach on Jul. 29, 1980, recognizes that trajectory type firearms must be fired with the weapon barrel in a vertical plane for accuracy. Rusbach provides for such leveling only in a crude liquid containing transparent container of considerable width as best seen in Rusbach's FIG. 24. Markings along the outer edges of the container allow the marksman to determine if the sighting device is canted prior to firing. This is similar to leveling a jug of water by assuring the water height is the same on each side of the jug. During the time the eyes focus from one side of the jug to the other, the jug must be held perfectly motionless. In practice, it is difficult, if not impossible, to align on a target and then check both sides of a liquid container at once while simultaneously holding a firearm motionless. Of course, if the width of the liquid container is reduced, the visual cues become easier to obtain but the accuracy of the leveling is sacrificed. Surface tension effects of the liquid become significant in a narrow liquid container so as to destroy the effectiveness of the intended operation. By contrast, the bubble type spirit level of the instant invention provides an easily seen accurate indication of level without requiring the eye to be continually refocused. The Rusbach leveling device is also formed as an integral part of his complex overall sighting mechanism and thus cannot be attached to another existing sighting system as is the intent of a notable feature of the instant invention.
U.S. Pat. No. 3,556,666, issued to Lichtenstern on Jan. 19, 1991, shows a telescopic gunsight with a built-in adjustable level means including interior illumination. The complex level means is formed as an integral part of the gunsight so as to be visible in the optical field of view of the scope thus unduly restricting a shooter's vision. The integral construction prevents the level of Lichtenstern from being attached to a different existing sighting system, whereas the visibility of the level indicator within the optical field of view reduces the size and usefulness of the view field for other uses particularly crucial to hunting, such as target acquisition. By contrast, it is easily possible and intended that the present invention be added to existing sighting systems. Also, the original field of view is left entirely unrestricted by the invention presented here.
U.S. Pat. No. 3,568,324, issued on Mar. 9, 1971 to Jorczak, shows a flip-up auxiliary sight attachment for hand-held firearms. Although the attachment is not used for leveling the firearm, the type of flip-up hinge and bracket used would be suitable for mounting the leveling device of the instant invention. The disclosure of Jorczak is hereby incorporated by reference.
U.S. Pat. No. 2,243,793, issued to Cummins on May 27, 1941, shows an early cant indicator for telescopic rifle sights. The pendulum leveling means must be formed as an integral part of the scope with a slot cut in the scope barrel thus preventing the leveling device from being easily added to existing sighting devices. In addition, the pendulum rod indicator interferes with normal vision of the scope cross-hairs and there is no way to move the leveling device to an unobtrusive non-use position. By contrast, the instant invention does not interfere with the normal sight field of view and can be easily pivoted out of the way for transport or storage.
None of the above inventions and patents, taken either singly or in combination, is seen to anticipate or make obvious the instant invention as claimed.